1. Field of the Invention
The present invention relates to an electrical connector for a circuit board.
2. Description of the Related Art
A connector of this type is disclosed in Japan patent application Kokai No. 07-142130.
In this known connector, a plurality of terminals are shaped by stamping a flat metal material maintaining its flat surfaces, and provided in a housing with certain intervals so as to be parallel to each other. The plurality of terminals are similar in their shapes, and have connection sections which protrude outward from the housing and have connection surfaces at their lower rear edges. Each terminal is connected to a circuit board by soldering each connection surface to a corresponding circuit section. In addition, each terminal has a contact section at the front end of its deflectable or flexible arm in the housing, so that a flat cable is to be placed thereon when it is inserted from an open mouth of the housing. Then, the flat cable elastically contacts with the contact section by turning a movable piece over to a closed position, which is supported at the open mouth so as to freely turn over. The connection surfaces of the terminals are provided in the same plane at a time of insertion of the terminals into the housing so as to be parallel to each other with certain intervals.
It is desirable that the connector of this type is smaller than ever before, while it has as many terminals as possible. Since the terminals are flat-shaped, shortening the intervals between the terminals can attain high-density arrangement of the terminals and a small size of the connector. However, although a small connector can be made from the point of view of the manufacturing, the connection surfaces are so close each other that there is a problem of short-circuit by a flow of soldering paste in use.
Accordingly, it is an object of the present invention to provide a compact electrical connector for a circuit board without such problems as described above, thereby enabling higher density arrangement of the terminals.
According to the present invention, a plurality of flat-sheet terminals are held in corresponding receiving slots of a housing in a direction parallel to its sheet surface of the terminal. Each terminal has a contact section to contact with a flat cable and a connection section to connect with a corresponding circuit section of a circuit board. The plurality of terminals are arranged in a direction perpendicular to the sheet surface, being parallel to each other, while their connect sections are faced to the same side. The housing has an open mouth to insert and place the flat cable onto the connection section of the plurality of the terminals at an opposite side of the housing to the connection section, and a movable member which is movably supported at the open mouth to press the flat cable towards the contact sections.
In the electrical connector for a circuit board of the present invention, the connection section is formed as an end section of the terminal, protrudes outward from a bottom surface of the housing, and has a connection surface to contact with the circuit section by its surface. The connection surfaces of the adjacent terminals are provided to be staggered in the receiving direction of the terminal to the housing.
According to the present invention, the connection surfaces of adjacent terminals are provided to be staggered in the receiving direction of the terminal, so that each interval between the connection surfaces of adjacent terminals in the same alignment line are at least twice longer than the one between the adjacent terminals. As a result, soldering of the connection section onto the circuit board can be done without problems in spite of the high-density arrangement of the terminals.
According to the present invention, it is desirable that the connection surfaces of the adjacent terminals are staggered without any overlapping between the adjacent contact surfaces. Even if the connection surfaces are staggered with some overlapping between the adjacent contact surfaces, problems related to a flow of soldering paste can be lessened. However, to certainly prevent the problems related to the soldering flow, the connection surfaces are preferably staggered without any overlapping between the adjacent connection surfaces.
The plurality of the terminals can be comprised of different types of terminal groups, and the terminals of a first terminal group and terminals of a second terminal group can be alternately staggered in a receiving direction of the terminal. Thus, even if all the terminals of the first and second terminal groups are inserted to the same receiving position in the receiving direction, or even if the contact sections are provided at the same position, adjacent connection surfaces can be shifted with certain intervals in the receiving direction as long as the connection sections are shifted.
Moreover, according to the present invention, the connection section of the terminal of at least one of the terminal groups can be at least partially held in the housing, and the connection surface which is an end surface of the connection section can be designed to expose outside of the bottom surface of the housing. By doing this, the connection section which is partially held in the housing can be more firmly retained to the housing, and simultaneously the connector can be smaller in the receiving direction of the terminal for the size of the portion of the connection section held in the housing.
Even if the connection section is in the housing, the connector can connect with a circuit board as long as the connection surface is exposed to outside of the housing.
The different types of terminal groups are desirable to have the same distance between the contact section and the connection section. In this case, electrical lengths (signal transmission lengths) are the same among those terminals, so that the electrical properties and transmission time of signals are not fluctuated, especially on high-speed transmission.